In the rolling of a metal or other material, particularly in the rolling of a plate material, it was conventionally demanded that the wedge (thickness variation in the direction of the plate width) be eliminated. More specifically, it was demanded that the plate thickness on the work side be equal to the plate thickness on the drive side. Formerly, while there was no plate material after mill roll replacement, the roll gap was reduced by a force, for instance, of 1000 or 1500 tons to ensure that the same rolling force is applied to the work side and drive side.
In general, however, the rolled plate varied in plate thickness. More specifically, the plate thickness on the work side differed from the plate thickness on the drive side. This plate thickness difference was caused, for instance, by the difference of a mill elastic constant in a mill housing between the work side and load side, the mill hysteresis difference between the work side and load side, or the slab plate thickness between the work side and drive side.
A conventional technology disclosed, for instance, by Patent Document 1 uses a wedge measuring instrument, which is installed at the outlet side or inlet side of a rolled material, to measure the amount of wedge. When the wedge is measured on the outlet side, this technology exercises feedback control in accordance with the measured amount of wedge. When the wedge is measured on the inlet side, this technology exercises feed forward control while using the load differential between the right- and left-hand sides of a roll and the load applied to a side guide. In this manner, this technology simultaneously suppresses the camber and wedge (refer to Patent Document 1, for example).
[Patent Document 1]
Japanese Patent Laid-Open No. 210513/2002